#include <stdio.h>
int main(){
    int i=0;
    char s1[40],s2[40];
    printf("input s2:");
    gets(s2);
    for(i=0;s2[i]!='\0';i++){
    s1[i]=s2[i];
    }
    s1[i]='\0';
    printf("s1:%s",s1);
}